Mobile UI: Deploying

This guide covers deploying your Expo app using EAS (Expo Application Services) CLI. EAS allows you to:

  • Build native apps for iOS and Android
  • Create preview builds for testing
  • Publish updates over-the-air (OTA)
  • Submit apps to app stores

Prerequisites

  • An Expo account (free at expo.dev)
  • EAS CLI installed
  • Your app configured in app.json or app.config.js

Installation

1. Check if EAS CLI is Already Installed

First, check if you already have EAS CLI installed:

eas --version

If you see a version number (e.g., 5.0.0), EAS CLI is already installed and you can skip to the next step. If you get a “command not found” error, proceed to install it.

2. Install EAS CLI

If EAS CLI is not installed, install it globally:

npm install -g eas-cli

Or use npx without global installation (no install needed):

npx eas-cli --version

Note: Using npx doesn’t require installation, but you’ll need to use npx eas-cli for every command instead of just eas.

3. Login to Expo

eas login

This will prompt you to:

  • Enter your Expo account email
  • Enter your password
  • Or open a browser to authenticate

If you don’t have an account, create one at expo.dev/signup.

4. Navigate to Your Project

Navigate to your mobile project directory:

cd mobile

Note: The project is already configured with eas.json and app.json files, so you don’t need to run eas init or manually configure these files.

Configuration

The project already includes the necessary configuration files:

EAS Configuration (eas.json)

The eas.json file is already configured with three build profiles:

  • development: For development builds with Expo Dev Client

    • Includes simulator builds for iOS
    • Uses development API URL (https://dev.tma.unca.info)

  • preview: For testing on physical devices (not app stores)

    • Creates installable .apk files for Android
    • Uses development API URL

  • production: For app store submissions

    • Creates production builds
    • Uses production API URL (https://tma.unca.info)

All profiles are configured with Node.js 20.18.0 and the appropriate environment variables.

App Configuration (app.json)

The app.json file is already configured with:

  • App name, slug, and version
  • iOS bundle identifier and Android package name
  • Icon and splash screen settings
  • Expo project ID (already linked to expo.dev)

You can modify these settings if needed, but the defaults are ready for deployment.

Building Your App

Preview Build (For Testing)

Create a preview build for testing on physical devices:

For Android:

eas build --platform android --profile preview

For iOS:

eas build --platform ios --profile preview

For both platforms:

eas build --platform all --profile preview

What happens:

  1. EAS uploads your code to Expo’s servers
  2. Builds your app in the cloud
  3. Provides a download link when complete
  4. You can install the .apk (Android) or .ipa (iOS) on your device

Note: For iOS, you’ll need an Apple Developer account ($99/year) to install on physical devices. For Android, you can install the .apk directly.

Production Build (For App Stores)

When ready to submit to app stores:

eas build --platform all --profile production

This creates builds ready for:

  • iOS: App Store submission
  • Android: Google Play Store submission

Publishing Updates (OTA)

After building your app, you can push JavaScript updates without rebuilding using OTA (Over-The-Air) updates. This allows you to update your app’s JavaScript code without going through the app store review process.

When to Use OTA Updates

OTA updates are appropriate for:

  • JavaScript/TypeScript code changes - Bug fixes, new features, UI improvements
  • React Native component updates - Changes to your React components and screens
  • Business logic updates - Changes to how your app processes data
  • Styling changes - Updates to colors, layouts, fonts
  • Configuration changes - API endpoints, feature flags
  • Quick bug fixes - Fixing issues without waiting for app store approval

When You Need a New Build

You must create a new build (not just an OTA update) when you:

  • Change native dependencies - Adding or updating packages that include native code (e.g., expo-camera, expo-location, native modules)
  • Modify app.json or app.config.js - Changes to app name, version, bundle identifier, icons, splash screens, permissions
  • Update Expo SDK version - Upgrading to a new Expo SDK requires a new build
  • Change native code - Any modifications to iOS (Swift/Objective-C) or Android (Java/Kotlin) code
  • Add new permissions - New camera, location, or other device permissions require a new build
  • Change app version - Incrementing the version number in app.json typically requires a new build
  • Update native build tools - Changes to build configuration in eas.json that affect native compilation

How OTA Updates Work

  1. Publish an Update

    eas update --branch production --message "Bug fixes and improvements"

    This publishes your latest JavaScript bundle to all users with the production build. Users will receive the update automatically the next time they open the app (if they have an internet connection).

  2. View Update Status

    eas update:list

    Shows all published updates and their status, including which users have received the update.

  3. Rollback an Update

    If an update causes issues:

    eas update:rollback

    This reverts to the previous update, allowing you to quickly fix problems without creating a new build.

Best Practices

  • Test updates thoroughly before publishing to production
  • Use branches to test updates on development/preview builds before pushing to production
  • Monitor update status to ensure users are receiving updates
  • Keep builds up to date - OTA updates only work for users who have a compatible build installed
  • Version your updates - Use descriptive messages to track what changed in each update

Submitting to App Stores

iOS App Store

  1. Build for production:

    eas build --platform ios --profile production

  2. Submit to App Store:

    eas submit --platform ios

    This will:

    • Ask for your Apple ID credentials
    • Upload your app to App Store Connect
    • Start the App Store review process

Google Play Store

  1. Build for production:

    eas build --platform android --profile production

  2. Submit to Play Store:

    eas submit --platform android

    This will:

    • Ask for your Google Play credentials
    • Upload your app to Google Play Console
    • Start the Play Store review process

Environment Variables

For production builds, set environment variables in eas.json:

{
  "build": {
    "production": {
      "env": {
        "EXPO_PUBLIC_API_URL": "https://api.yourapp.com"
      }
    }
  }
}

Or use EAS secrets for sensitive values:

eas secret:create --name EXPO_PUBLIC_API_URL --value https://api.yourapp.com --scope project

Common Commands

# Check build status
eas build:list

# View build details
eas build:view [BUILD_ID]

# Cancel a build
eas build:cancel [BUILD_ID]

# Download a build
eas build:download [BUILD_ID]

# View project info
eas project:info

# Update EAS CLI
npm install -g eas-cli@latest

Resources

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UNC Asheville Department of Computer Science